Radio signaling system



6 19 Sept 27 R. s. OHL

RADIO SIGNALING SYSTEM Filed Ney. 23, 19,25

` INVENTOR e5: 0/0

ATTORNEY Patented Sept. 6), 1927.

UNITEDv STATESI r ,1,641,289 PATENT OFFICE.

RUSSELL s.' OHL, or NEW Yonx, N. Y., AssIoNon 'ro' AMERICAN TELEPHONE AND TELEGRAPH COMPANY, A CORPORATION or NEW YORK.

RADIO SIGNALING SYSTEM.

This invention relates to, radiosignaling systems, and has yas its principal object the reduction of fading and distortion effectsfin the transmission and reception of signals by radio. i

When radio signals are transmitted and received. on a single wave length, the undesirablefading and distortion edects are considerable. Applicant proposesy tor send 10 and receive the signals Von a plurality of wave lengths simultaneously, as explained f below.

Applicants methods of and means for radio signaling of the nature indicated above in general provide for` the -sending of the 4ception. of the several modulated radio frequencies separately, and the beating of thereceived frequencies to a common intermediate frequengyvspjhatthesignals may be limited and -passed through the same intermediate frequency amplifier without trouble from frequency changes on any one of the channels. In orderl that this may be accomplished, two conditions must be met,A

.(1) that the relation between the frequencies of the severa'l channels be constant, and (2) thaty the same intermediate frequency be used for amplicat-ion.

Applicants invention will be more clearly understood when the following scription is read with reference to the accompanying drawing. The specific arrangeq ment shown anddescribed contemplates the sending of the signal on two frequencies.

The drawing shows diagrarnmatica'lly#theV circuits of the trasmit'tingisfion and the receiving station. Such apparatus as is well known in the art is /shown symbolically in cases inwhich v1 such a showing serves to rsimplifthe diagram. The rad io'frequencies and the intermediate 4frequency indicated are chosen arbitrarily for purposes of specific description.

With reference to the details of the drawing, at the transmitting station -there is a master oscillator y1 which produces a frequency of1,000 kilocycles (ke), for in stance. In one channel this frequenc is .multiplied to 2,000 kc. by means o the armonic producer and selector 2, while in the second channel the basic frequency is mul. `Vvtiplicd to 3,000 kc. by the harmonic producer and selector 3. The 2,000 kc. frequency is fed intothe modulator-amplifier 5; ma the signal on va plurality of frequencies, the req detailed de-- 3-,000 kc. frequency is fed into themodulator ampllfier 6. The telephone transmitter 4 is inductively connected to these two modulator-amplifiers, and each high frequency is modulated with the signal, the 2,000 kc. frequency inthe modulator-amplifier 5, and the 3,000 kc. frequency in the modulatoramplifier 6, Thus there are two high frequencies modulated with the same signal. The 2,000 kc. frequency, modulated,'is sent out from the antenna 7, and the 3,000 kc. frequency, likewise modulated, is sent out from the -second channel on antenna 8.v

At the receiving station the antenna 9 re# ceives the modulated 2,000 kc. carrier freucncy, and from this antenna this frequency is fed into the demodulator 10. Likewise the modulated 3,000 kc.. carrier frequency is. received on the antenna 11, and the frequency fed into the dexnodulator 12.

t'the receiving station there is a second master Oscillator 13 producing, for instance, y 1,000 kc. The requirement is that the frequency produced be a sub-multiple of both the transmitting carrier frequencies, here taken to be 2,000 kc. and 3,000 kc., for the purpose of illustration. This frequency is multiplied in one channel to 2,000 kc. by the .harmonic producer and selector 14, and to 3,000 kc. inthe second channel by the harmonic producer and selector 15. A third oscillator 16 is caused to produce the freuency of kc., which frequency is added to the 2,000 kc. frequency and to the 3,000 kc. lfrequency in the modulators 17, andv18, rerspectivelyanln the rst channel, the result of this modulation is passed through the 2,100 kc.` filter 19, and the 2,100 kc. component is fed into the demodulator 10. Likewise, in the other channel the result of the combination of the 3,000 kc. frequency and' y the 100 kc. frequency is passed through the 3,100 kc. filter 20, and the 3,100 kc. component is fed into the demodulator 12.

Thus, inthe first channel, the 2,000 kc.4 frequency, modulated with the signal, is beaten with a frequency of 2,100 kc., and. in the second channel the received frequenc of the 3,000 kc., modulated with the signa is beaten with the frequency of 3,100 kc. The filter 21 in the rst channel of the receiving station selects the 100 kc. component upon which is superimposed, of course, the signal frequency. Also in the second'chan- ,nel of the receiving station the filterv 22 110 ico rector 24, where the signal `isdetected, as

, selects the intermediate frequency of 100 kc.

with the signal' frequency superimposed thereon. From the filters 21 and 22, the two channels ofthe receiving circuit are united in the intermediate frequency amplifier 23. It is seen that the two intermedlate lfrequencies Aeach modulated with the signal,

whichA are passed into this amplifier, are equal. From the amplifier 23, the 'intervmediate frequency current carrying the signal, means for receiving separately the two modulated yradio frequencies and beating them with frequencies of such values that there is produced a common 4intermediate frequency, means for uniting and amplifying the intermediate frequency cur-` rents, and the usual means for detecting thesi al. 7

Wlnle applicants invention has beendisclosed in one specific embodiment,v4 which is 'deemed desirable, it is to loe understood that it is capable of 'embodiment in many other and different forms without a departure from the truel scope of the invention as defined in the appended claims.

' What is claimed is:

l. The method of reducing fading and ydistortion eects in the transmission of signalsby radio, which consists in transmitting a given signal on a plurality of wave lengths, beating the several received frequencies to a common intermediate frequency, unitin and amplifying the result-ant currents, an detecting the signal.

2. The methodofreducing fading and dis- 1toortion edects in the transmission of signals girven signal on a plurality of wave lengths simultaneously, beating the several received frequencies to a4 common intermediate frequency, uniting and amplifying the resultant currents, and detecting the s1 nal.

3. y'lhe method of reducing fading and distortion eects in the transmission of signals ley-radio which consists in transmitting oscillations o-f a plurality of radio frequencies each modulated with the signal, 'receiving separately the several modulated radiofrequencies,'beating the several received frequencies toA a common intermediate frequency, unitin and amplifying the resultant currents, and etecting the signal.

4f. The method ofreducing fading anddistortion effects in the transmission of'signals by radio, which consists in transmitting simultaneously oscillations of a plurality of radio frequencies eachmodulated with the signal, receiving separately4 the several modulated radio frequencies, beating the sev I eral received frequencies to a common intermediate frequency, uniting and amplifying the resultant currents, and detecting the signal.

5. The 'method' ofreducing fading andv distortion effects in the transmission of signels by radio, the transmitting station oscillations of a plurality of radio frequencies, modulating each radio' frequency with the signal, transwhich consists in producingl at4 mitting eachmodulated radio frequency sepsignal, means for receiving separately theI several'modulated radio frequencies,means for beating the several received frequencies tota common intermediate frequency, means for unitingand amplifying the intermediate frequency lcurrents, and means for detecting the'signal.

- -7. In a radio signaling system, meansfoi;

transmitting simultaneously oscillationsof aplurality of radio frequencies each modu-l lated with a signal, means for receiving separately the several modulated radio frequen# cies, means for beating the several'received frequencies to a common intermediate frequency, means for uniting and amplifying the intermediate frequencyl currents, and means for detecting the signal. .iy

8. In a radio signaling s stem comprising a transmitting station an a receiving station, means at the transmitting station for producing oscillations of a plurality of difradio, which consists in transmittingLferent high frequencies, means for modulatoscillations with signal, means for sending out lseparately the vmodulated oscillations, se arate means for receiving the sev-- eral modu at thereceivin'g station fdrbeating. the modulated high frequency oscillations mon intermediate frequency, means for uniting and' amplifying vthe intermediate frequency currents, and means for detecting the signal. 9. In a radio signaling'system, the combination of a transmission station and a receiving station; said transmitting station comm prising a signal transmitter, means for producin oscillations of a plurality of different l high requencies, means for modulatin said oscillations with the signal transmitte and means for sending out se arately andsimultaneousl the modulate high frequencies,- and sai receiving station comprising se l rate means for receiving the several high f' atedhigh Vfrequency waves, means lio \ to a comTM quencies, means for beating the several received frequencies to a common intermediate frequency, means for uniting the intermediate frequency currents, means for amplifying said currents, and means for detecting the signal.

10. In a radio signaling system, the combination of a transmitting station and a receiving station; said transmitting station comprising a signal transmitter, means for producing oscillations of a plurality of different high frequencies, means for modulating said oscillations with the signal transmitted,and means for sending out separately and simultaneously the modulated high frequencies; and said receiving station comprising separate means for receiving the several selected,

high frequencies, means for-producing oscillations corresponding in frequency to those produced at the transmitting station, means forsuperimposing a common intermediate frequency upon said oscillations to produce beatin frequencies means for combining each o said beating requencies with the nearest received frequency, means for selecting from the resultant oscillations the intermediate frequencies with the signal superimposed thereon, means for uniting the frequencies means for amplifying the resultant current, and means for detecting the si al.

In testimony whereof, I save signe my name to this specification this 20th lday of November, 1925.

RUSSELL S. OHL. 

